Feature/blinded version

[ThomasSession]

SES-2483 - Updated Version API

We need the app to periodically (every 4hours at most) check the latest app version,
which is available on the File server API.

Two new endpoints were added to libsession to help with the required headers for the new version endpoint.
JNI bridging added in.

[bemusementpark]

inline

[bemusementpark]

would perhaps be ideal to just have one by lazy somewhere that we reference instead of loading this thing for the 8th time.

IDK if it's optimised away sometimes/always/never, but at least when we loaded a lib way to many times, it crashed on some devices.

[bemusementpark]

so... you could perhaps more clearly:

val timestampSeconds = System.currentTimeMillis().milliseconds.inWholeSeconds

as it's useful to put units in the variable name if it is not contained in the type.

alternatively

val timestamp = System.currentTimeMillis().milliseconds
val signature = BlindKeyAPI.blindVersionSign(secretKey, timestamp.inWholeSeconds)
...
"X-FS-Timestamp" to timestamp.inWholeSeconds.toString(),

[bemusementpark]

Seeing as there's all of these named vals that are simple enough to inline, they may as well be named params, and you get a little bit more safety that they're in the right order etc.

Suggested change

	val json = JsonUtil.fromJson(result, Map::class.java)
	val statusCode = json.getOrDefault("status_code", 0) as Int
	val version = json.getOrDefault("result", "") as String
	val updated = json.getOrDefault("updated", 0.0) as Double
	return VersionData(statusCode, version, updated)
	return JsonUtil.fromJson(result, Map::class.java).let {
	VersionData(
	statusCode = it["status_code"] as? Int ?: 0
	version = it["result"] as? String ?: ""
	updated = it["updated"] as? Double ?: 0.0
	)
	}

[bemusementpark]

could probably inject without much trouble